the Tibialis anterior by a splitting of its fibers. The other limb extends downward and medialward, to be attached to the border of the plantar aponeurosis, and passes over the tendons of the Extensor hallucis longus and Tibialis anterior and also the vessels and nerves.

Laciniate Ligament (ligamentum laciniatum; internal annular ligament).The laciniate ligament is a strong fibrous band, extending from the tibial malleolus above to the margin of the calcaneus below, converting a series of bony grooves in this situation into canals for the passage of the tendons of the Flexor muscles and the posterior tibial vessels and tibial nerve into the sole of the foot. It is continuous by its upper border with the deep fascia of the leg, and by its lower border with the plantar aponeurosis and the fibers of origin of the Abductor hallucis muscle. Enumerated from the medial side, the four canals which it forms transmit the tendon of the Tibialis posterior; the tendon of the Flexor digitorum longus; the posterior tibial vessels and tibial nerve, which run through a broad space beneath the ligament; and lastly, in a canal formed partly by the talus, the tendon of the Flexor hallucis longus.

FIG. 442 The mucous sheaths of the tendons around the ankle. Medial aspect. (See enlarged image)

Peroneal Retinacula.The peroneal retinacula are fibrous bands which bind down the tendons of the Peronæi longus and brevis as they run across the lateral side of the ankle. The fibers of the superior retinaculum (external annular ligament) are attached above to the lateral malleolus and below to the lateral surface of the calcaneus. The fibers of the inferior retinaculum are continuous in front with those of the cruciate crural ligament; behind they are attached to the lateral surface of the calcaneus; some of the fibers are fixed to the peroneal trochlea, forming a septum between the tendons of the Peronæi longus and brevis.

The Mucous Sheaths of the Tendons Around the Ankle.All the tendons crossing the ankle-joint are enclosed for part of their length in mucous sheaths which have an almost uniform length of about 8 cm. each. On the front of the ankle (Fig. 441) the sheath for the Tibialis anterior extends from the upper margin of the transverse crural ligament to the interval between the diverging limbs of the cruciate ligament; those for the Extensor digitorum longus and Extensor hallucis longus reach upward to just above the level of the tips of the malleoli, the former being the higher. The sheath of the Extensor hallucis longus is prolonged on to the base of the first metatarsal bone, while that of the Extensor digitorum longus reaches